Monolithic ceramic electronic component

ABSTRACT

When a monolithic ceramic electronic component is viewed from either one of end surfaces thereof, an outer electrode includes a solder-repellent portion and a solder-receivable portion. The solder-repellent portion covers the central portion of an end surface of a ceramic laminate body. The solder-receivable portion includes portions disposed on two opposing sides of the solder-repellent portion. When the monolithic ceramic electronic component is mounted on the circuit board, solder does not adhere to a portion around the central portion of the end surface. Thus, expansion and contraction that occur as a result of application of an AC voltage are not significantly transmitted to the circuit board. Consequently, vibrations of the circuit board are reduced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to monolithic ceramic electroniccomponents, and particularly to a monolithic ceramic capacitormanufactured by a method of reducing acoustic noise generated when anelectric field is applied to the monolithic ceramic capacitor mounted ona circuit board.

2. Description of the Related Art

As electronic devices produce increasingly less noise, acoustic noisehas become more noticeable, caused by vibrations of monolithic ceramiccapacitors (referred to as “monolithic capacitors”, below) in powercircuits or other components of various devices, such as laptopcomputers, mobile phones, or digital cameras.

Japanese Unexamined Patent Application Publication No. 2010-186884describes that acoustic noise occurs when an AC voltage is applied to amonolithic capacitor mounted on a circuit board due to electrostrictivevibrations of the monolithic capacitor propagating through the circuitboard.

FIG. 16 and FIG. 17 are drawings illustrated on an online web page“Examples of Noise Countermeasures” of Murata Manufacturing Co., Ltd.,searched on Mar. 1, 2012, through Internet URL“http://www.murata.co.jp/products/capacitor/solution/naki.html”. When anAC voltage is applied to a monolithic capacitor 110, the monolithiccapacitor 110 expands and contracts in directions indicated by the boldarrows, as illustrated in FIG. 16, due to the electrostrictive effect ofthe ferroelectric ceramic of the monolithic capacitor 110. In FIG. 16,the WT cross section denotes a cross section defined by the width andthe thickness of the monolithic capacitor 110. The LT cross sectiondenotes a cross section defined by the length and the thickness of themonolithic capacitor 110. The LW cross section denotes a cross sectiondefined by the length and the width of the monolithic capacitor 110. Thebroken lines indicate the extent to which the monolithic capacitor 110expands and contracts when viewed in these cross sections.

As illustrated in FIG. 17, when an AC voltage is applied to themonolithic capacitor 110 that is mounted on the circuit board 101 via asolder 102, the monolithic capacitor 110 expands and contracts. Thisexpansion and contraction of the monolithic capacitor 110 leads todeformation of the circuit board 101 via the solder 102. Thus, thecircuit board 101 vibrates in directions such that the surface of thecircuit board 101 rises and falls. When the cycle of vibrations of thecircuit board 101 falls within a frequency range (20 Hz to 20 kHz) thatis audible to human beings, human ears perceive the vibrations asacoustic noise.

These are problems not only for the monolithic capacitor 110 includingtwo outer electrodes 114 but also for a three-terminal monolithiccapacitor including three outer electrodes 114. Further, these problemscan occur not only in the monolithic capacitor 110, but also in anymonolithic ceramic electronic component including a monolithic LCfilter.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a monolithicceramic electronic component that overcomes the problems describedabove.

A monolithic ceramic electronic component according to a preferredembodiment of the present invention is a monolithic ceramic electroniccomponent that includes a ceramic laminate body having a cuboid orsubstantially cuboid shape and including dielectric ceramic layers andinternal electrodes that are alternately stacked on top of one another,the ceramic laminate body including an outer periphery defined by anupper surface, a lower surface, two side surfaces, and two end surfacesthat are perpendicular or substantially perpendicular to the uppersurface, the lower surface, and the two side surfaces; and an outerelectrode arranged on at least one of the end surfaces so as to beelectrically connected to the internal electrodes. The outer electrodeincludes a solder-repellent portion to which molten solder adheres and asolder-receivable portion to which molten solder does not adhere. Whenthe monolithic ceramic electronic component is viewed from the endsurface on which the outer electrode is disposed, the solder-repellentportion is arranged so as to cover a central portion of the end surface,and the solder-receivable portion includes portions disposed on twoopposing sides of the solder-repellent portion so as to sandwich thesolder-repellent portion.

When the monolithic ceramic electronic component is viewed from the endsurface on which the outer electrode is disposed, the outer electrodemay preferably have a quadrangular or substantially quadrangular shape,and the solder-receivable portion may preferably be arranged so as toextend over four corner portions of the outer electrode.

When a direction in which the dielectric ceramic layers are stacked is avertical direction and the monolithic ceramic electronic component isviewed from the end surface on which the outer electrode is disposed,the solder-receivable portion may preferably include upper and lowerportions of the solder-receivable portion in the vertical direction thatare symmetrical with each other.

The ceramic laminate body preferably may include a main laminate portionand a margin portion disposed around the main laminate portion, the mainlaminate portion being one in which the dielectric ceramic layers andthe internal electrodes are alternately stacked on top of one anotherand are into contact with one another, the margin portion being one inwhich the dielectric ceramic layers are stacked on top of one another.When the monolithic ceramic electronic component is viewed from the endsurface on which the outer electrode is provided, an area of thesolder-repellent portion may preferably be greater than an area of themain laminate portion but less than an area defined by an outerperiphery of the margin portion.

The outer electrode may preferably cover a portion of the ceramiclaminate body, the portion extending from the end surface to portions ofthe upper surface, the lower surface, and the two side surfaces. Whenthe monolithic ceramic electronic component is viewed from one of theside surfaces on which the outer electrode is provided, thesolder-repellent portion may be arranged so as to partially extend overa portion of the outer electrode provided on the side surface.

The solder-repellent portion preferably may be defined by asolder-resistant film attached to the outer electrode.

The solder-resistant film may preferably be made of a heat-resistantresin that is not deformed at a soldering temperature.

The solder-repellent portion may be defined by an oxidized portion ofthe outer electrode.

The solder-receivable portion may preferably be provided in a portion ofthe outer electrode that is exposed to the outside.

In the monolithic ceramic electronic component according to variouspreferred embodiments of the present invention, the solder-repellentportion is arranged so as to cover the central portion of the endsurface of the ceramic laminate body. Thus, molten solder is preventedfrom adhering to the central portion of the end surface. Consequently,acoustic noise generated when an AC voltage is applied to the monolithicceramic electronic component mounted on the circuit board is reduced.Further, since the solder-receivable portion includes portions disposedon two opposed sides of the solder-repellent portion, the monolithicceramic electronic component can be mounted on the circuit boardregardless of whether its upper surface faces upward or downward. Inaddition, the monolithic ceramic electronic component can be securelyconnected to the circuit board after being mounted on the circuit board.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a monolithic ceramic capacitor according to a firstpreferred embodiment of the present invention.

FIG. 2 illustrates a state in which the monolithic ceramic capacitorillustrated in FIG. 1 is mounted on a circuit board.

FIG. 3 illustrates a monolithic ceramic capacitor according to a firstmodification of a preferred embodiment of the present invention in whichthe solder-repellent portion illustrated in FIG. 1 is modified.

FIG. 4 illustrates a monolithic ceramic capacitor according to a secondmodification of a preferred embodiment of the present invention in whichthe solder-repellent portion illustrated in FIG. 1 is modified.

FIG. 5 illustrates a monolithic ceramic capacitor according to a thirdmodification of a preferred embodiment of the present invention in whichthe solder-repellent portion illustrated in FIG. 1 is modified.

FIG. 6 illustrates a monolithic ceramic capacitor according to a fourthmodification of a preferred embodiment of the present invention in whichthe solder-repellent portion illustrated in FIG. 1 is modified.

FIG. 7 illustrates a monolithic ceramic capacitor according to a fifthmodification of a preferred embodiment of the present invention in whichthe solder-repellent portion illustrated in FIG. 1 is modified.

FIG. 8 illustrates a monolithic ceramic capacitor according to a secondpreferred embodiment of the present invention.

FIG. 9 illustrates a monolithic ceramic capacitor according to a sixthmodification of a preferred embodiment of the present invention in whichthe outer electrode illustrated in FIG. 8 is modified.

FIG. 10 illustrates a monolithic ceramic capacitor according to aseventh modification of a preferred embodiment of the present inventionin which the outer electrode illustrated in FIG. 8 is modified.

FIG. 11 illustrates a monolithic ceramic capacitor according to a thirdpreferred embodiment of the present invention.

FIG. 12 illustrates a monolithic ceramic capacitor according to aneighth modification of a preferred embodiment of the present inventionin which the solder-repellent portion illustrated in FIG. 11 ismodified.

FIG. 13 illustrates a monolithic ceramic capacitor according to a ninthmodification of a preferred embodiment of the present invention in whichthe solder-repellent portion illustrated in FIG. 11 is modified.

FIG. 14 illustrates a circuit board on which the monolithic ceramiccapacitor illustrated in FIG. 11 is mounted.

FIG. 15 illustrates a monolithic ceramic capacitor according to a fourthpreferred embodiment of the present invention.

FIG. 16 illustrates a state in which an AC voltage is applied to a knownmonolithic ceramic capacitor.

FIG. 17 illustrates a state where an AC voltage is applied to the knownmonolithic ceramic capacitor mounted on a circuit board.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First PreferredEmbodiment

As illustrated in FIG. 1, a monolithic ceramic capacitor 10 includes aceramic laminate body 13 including a plurality of alternating layers ofdielectric ceramic layers 11 and internal electrodes 12, and a pair ofouter electrodes 14 provided on both end portions of the ceramiclaminate body 13. The outer periphery of the ceramic laminate body 13 isdefined by an upper surface 8, a lower surface 9, two side surfaces 16,and two end surfaces 15 perpendicular or substantially perpendicular tothe upper surface 8, the lower surface 9, and the two side surfaces 16.The internal electrodes 12 are arranged such that each pair of adjacentelectrodes 12 face each other with one dielectric ceramic layer 11interposed therebetween. One of the pair of opposing internal electrodes12 is connected to the corresponding one of the outer electrodes 14, andthe other one of the pair opposing internal electrodes 12 is connectedto the other outer electrode 14. The outer electrode 14 is primarilyarranged so as to cover a corresponding one of the end surfaces 15 ofthe ceramic laminate body 13, but also covers portions of the uppersurface 8, the lower surface 9, and both side surfaces 16 that arecontinuous with the end surface 15. Another outer electrode 14 issimilarly arranged to cover the other end surface 15.

Herein, for convenience purposes, the monolithic ceramic capacitor 10 isreferred to as a monolithic capacitor 10, the dielectric ceramic layer11 is referred to as a dielectric layer 11, and the ceramic laminatebody 13 is referred to as a laminate body 13. In a description of theorientation of the monolithic capacitor 10, the direction in which thedielectric layers 11 are stacked is referred to as a vertical direction,the direction in which the pair of outer electrodes 14 are arranged isreferred to as a lengthwise direction, and the direction orthogonal tothe vertical direction and the lengthwise direction is referred to as awidthwise direction.

The laminate body 13 preferably has a cuboid or substantially cuboidshape with the corners rounded off, for example. The outer electrodes 14provided on both end surfaces 15 of the laminate body 13 also preferablyhave a rounded shape so as to correspond to the shape of the corners ofthe laminate body 13. However, in the first preferred embodiment of thepresent invention, each end surface 15 of the laminate body 13 isunderstood to include the above-described rounded portions in additionto a flat portion. Thus, the end surfaces 15 are illustrated as beingentirely flat in FIG. 1 and the rounded portions are not illustrated.

In the first preferred embodiment, as illustrated in FIG. 1, the outerelectrodes 14 arranged over both end surfaces 15 of the monolithiccapacitor 10 each include a solder-repellent portion 17 and asolder-receivable portion 18. The solder-repellent portion 17 is aportion that does not allow molten solder to adhere thereto when themolten solder is brought into contact with the solder-repellent portion17 from the outside of the monolithic capacitor 10. Thesolder-receivable portion 18 is a portion that allows the molten solderto adhere thereto. The solder-repellent portion 17 is arranged so as tocover a central portion C of each end surface 15 of the laminate body 13when the monolithic capacitor 10 is viewed from the end surface 15. Thesolder-receivable portion 18 includes portions disposed on two opposingsides of the solder-repellent portion 17 in the vertical or widthwisedirection so as to sandwich the solder-repellent portion 17.

Specifically, when the monolithic capacitor 10 is viewed from the endsurface 15, preferably, each outer electrode 14 is substantiallyrectangular and the solder-repellent portion 17 is circular orsubstantially circular. The solder-repellent portion 17 is defined by asubstantially circular solder-resistant film 19 attached to the surfaceof the outer electrode 14. In other words, a portion covered by thesolder-resistant film 19 in FIG. 1 is the solder-repellent portion 17.On the other hand, the solder-receivable portion 18 is a portion of theouter electrode 14 that is not covered by the solder-resistant film 19.The solder-receivable portion 18 is arranged so as to extend over atleast four corner portions of the outer electrode 14. Thesolder-receivable portion 18 configured such that upper and lowerportions of the solder-receivable portion 18 are symmetrical withrespect to a horizontal line passing the central portion C.

Preferably, the solder-resistant film 19 is made of a material that isnot deformed at the soldering temperature, (for example, approximately139° C. or higher), such as a heat-resistant resin, for example. Eachouter electrode 14 preferably includes, for example, three layers ofcopper (Cu), nickel (Ni), and tin (Sn) or copper (Cu), nickel (Ni), andgold (Au). The materials of the outer electrodes 14 allow the moltensolder to adhere thereto when the molten solder is brought into contacttherewith. Examples of the material of the molten solder preferablyinclude a tin-silver-copper (Sn—Ag—Cu) alloy.

The dielectric layers 11 are preferably made of a ferroelectric materialsuch as barium titanate, for example. Therefore, when an AC voltage isapplied to the pair of outer electrodes 14 of the monolithic capacitor10, the polarities of the dielectric layers 11 are reversed and thus theelectrostrictive phenomenon occurs.

FIG. 2 illustrates a state in which the monolithic capacitor 10according to the first preferred embodiment is mounted on a circuitboard 1 via a solder 2. As illustrated in FIG. 2, molten solder adheresto the solder-receivable portions 18 of the monolithic capacitor 10 andfillets 3 are provided so as to connect the solder-receivable portions18 to the circuit board 1. However, the molten solder does not adhere tothe solder-repellent portions 17, that is, portions around the centralportion C of the end surfaces 15 and thus the fillets 3 are not formedover these portions.

As illustrated in FIG. 16, when an AC voltage is applied to themonolithic capacitor 10, portions around the central portion C of theend surfaces 15 expand and contract to a large extent. According to thefirst preferred embodiment, as illustrated in FIG. 2, the molten solderdoes not adhere to portions around the central portion C of the endsurfaces. Thus, expansion and contraction that occurs as a result ofapplication of an AC voltage is not substantially transmitted to thecircuit board 1. Consequently, vibrations of the circuit board 1 arereduced and acoustic noise is much less likely to be generated.

Further, as illustrated in FIG. 2, the molten solder adheres to thesolder-receivable portions 18. Thus, the fillets 3 are provided so as toconnect the solder-receivable portions 18 to the circuit board 1, thussecurely connecting the monolithic capacitor 10 and the circuit board 1together. When an AC voltage is applied to the monolithic capacitor 10,portions around the central portion C of the end surfaces 15 expand andcontract to a large extent, as illustrated in FIG. 16, but portionsother than the portions around the central portion C expand and contractto a smaller extent. Consequently, even when a fillet 3 is provided inportions other than the portions around the central portion C of the endsurfaces 15, expansion and contraction transmitted to the circuit board1 is relatively small and, thus, the effect of vibrations transmitted tothe circuit board 1 is insignificant.

Further, when the monolithic capacitor 10 is viewed from one of the endsurfaces 15 as illustrated in FIG. 2, the correspondingsolder-receivable portion 18 includes portions disposed on two opposingsides of the solder-repellent portion 17. Therefore, the monolithiccapacitor 10 can be mounted on the circuit board 1 regardless of whetherits upper surface faces upward or downward.

Preferably, each solder-receivable portion 18 is arranged so as toextend over four corner portions of the corresponding outer electrode14. As illustrated in FIG. 16, when the monolithic capacitor 10 isviewed from one of the end surface 15, the four corner portions of theouter electrode 14 expand and contract to a smaller extent than portionsother than the four corner portions. Thus, when the fillet 3 is providedover any one of the four corner portions of the outer electrode 14 andnot provided over portions other than the four corner portions,vibrations transmitted to the circuit board 1 are effectively reduced.

In addition, preferably, each solder-receivable portion 18 is configuredsuch that upper and lower portions are symmetrical with each other. Whenthe monolithic capacitor 10 is configured in this manner, each fillet 3will have substantially the same shape regardless of whether the uppersurface of the monolithic capacitor 10 faces upward or downward when themonolithic capacitor 10 is mounted on the circuit board 1. Consequently,the amplitudes of vibrations transmitted to the circuit board 1 aresubstantially the same in both cases, thereby stably reducing vibrationsregardless of whether the upper surface of the capacitor 10 faces upwardor downward.

In addition, as described above, the material of the solder-resistantfilm 19 is preferably, for example, a heat-resistant resin that is notdeformed at the soldering temperature. Thus, a portion to which thesolder is not to be adhered is maintained free from the solder at thesoldering temperature when the monolithic capacitor 10 is mounted on thecircuit board 1.

Here, a non-limiting example of a method of manufacturing the monolithiccapacitor 10 according to the first preferred embodiment will now bedescribed. First, an internal electrode 12 made of a material such as asilver-palladium (Ag—Pd) alloy, for example, is preferably printed onthe surface of a ceramic green sheet made of a barium-titanate-basedmaterial, for example. The printing operation is repeated until apredetermined number of ceramic green sheets each including the internalelectrode 12 are stacked on top of one another. Then, the stacked sheetsare fired at a predetermined temperature to form a laminate body 13.Further, conductive paste is applied to both end portions of thelaminate body 13 and the laminate body 13 is fired to form outerelectrodes 14. The process described thus far is substantially the sameas that in a known monolithic-capacitor manufacturing method.

In order to obtain the monolithic capacitor 10 according to the firstpreferred embodiment, solder-receivable portions 17 are also formed onportions of the outer electrode 14 provided on both end surfaces 15(these portions will also be referred to as end surface portions of theouter electrode 14). To this end, solder-resistant films 19 are attachedto the both end surface portions. The solder-resistant films 19 are, forexample, print-transferred thereto. Specifically, a printing platehaving a concave portion with a predetermined shape is filled with apaste material of the solder-resistant films 19. Then, the end surfaceportion of one of the outer electrodes 14 is brought into contact withthe printing plate. Thereafter, the outer electrode 14 is separated fromthe printing plate and the paste material that has adhered to the outerelectrode 14 is cured. The solder-resistance film 19 is similarlyattached to the end surface portion of the other outer electrode 14.Examples of other printing methods include roller transfer and pintransfer.

The monolithic capacitor 10 according to the first preferred embodimentcan be appropriately modified with regard to the position and/or theshape of the solder-repellent portions 17. FIGS. 3 to 7 illustratemonolithic capacitors according to some non-limiting exemplarymodifications.

FIG. 3 illustrates a monolithic capacitor 10 according to a firstmodification of a preferred embodiment of the present invention in whichthe solder-repellent portions 17 are modified. In FIG. 3, when themonolithic capacitor 10 is viewed from one of the end surfaces 15, asolder-repellent portion 17A is arranged so as to cover the centralportion C of the end surface 15. The solder-repellent portion 17A isdefined by a rectangular or substantially rectangular solder-resistantfilm 19A attached to the surface of the outer electrode 14. Asolder-receivable portion 18A includes portions disposed on two opposingsides of the solder-repellent portion 17A in the vertical or widthwisedirection so as to sandwich the solder-repellent portion 17A.

FIG. 4 illustrates a monolithic capacitor 10 according to a secondmodification of a preferred embodiment of the present invention in whichthe solder-repellent portions 17 are modified. In FIG. 4, when themonolithic capacitor 10 is viewed from one of the end surfaces 15, asolder-repellent portion 17B is arranged so as to cover the centralportion C of the end surface 15. The solder-repellent portion 17B isdefined by a solder-resistant film 19B having a widthwise-extendingstrip shape attached to the surface of the outer electrode 14.Solder-receivable portions 18B are located on two opposing sides of thesolder-repellent portion 17B in the vertical direction so as to sandwichthe solder-repellent portion 17B.

FIG. 5 illustrates a monolithic capacitor 10 according to a thirdmodification of a preferred embodiment of the present invention in whichthe solder-repellent portions 17 are modified. In FIG. 5, when themonolithic capacitor 10 is viewed from one of the end surfaces 15, asolder-repellent portion 17C is arranged so as to cover the centralportion C of the end surface 15. The solder-repellent portion 17C isdefined by a solder-resistant film 19C having a vertically-extendingstrip shape attached to the surface of the outer electrode 14.Solder-receivable portions 18C are located on two opposing sides of thesolder-repellent portion 17C in the widthwise direction so as tosandwich the solder-repellent portion 17C.

FIG. 6 illustrates a monolithic capacitor 10 according to a fourthmodification of a preferred embodiment of the present invention in whichthe solder-repellent portions 17 are modified. In FIG. 6, when themonolithic capacitor 10 is viewed from one of the end surfaces 15, asolder-repellent portion 17D is arranged so as to cover the centralportion C of the end surface 15. The solder-repellent portion 17D isdefined by an octagonal or substantially octagonal solder-resistant film19D attached to the surface of the outer electrode 14. Solder-receivableportions 18D are arranged in four corner portions of the end surfaceportion of the outer electrode 14 around the solder-repellent portion17D.

FIG. 7 illustrates a monolithic capacitor 10 according to a fifthmodification of a preferred embodiment of the present invention in whichthe solder-repellent portions 17 are modified. As illustrated in FIG. 7,the laminate body 13 includes a main laminate portion 13A and a marginportion 13B. The main laminate portion 13A includes dielectric layers 11and internal electrodes 12 that are alternately stacked on top of oneanother and bringing the dielectric layers 11 and the internalelectrodes 12 into contact with one another. The margin portion 13B isdisposed around the main laminate portion 13A by stacking the dielectriclayers 11 on top of one another. The main laminate portion 13A is aportion in which an electrostrictive phenomenon occurs when a voltage isapplied to the monolithic capacitor 10.

A solder-repellent portion 17E is defined by a quadrangular orsubstantially quadrangular solder-resistant film 19E attached to thesurface of the outer electrode 14. When the monolithic capacitor 10 isviewed from either one of the end surfaces 15, the area of thesolder-repellent portion 17E is preferably larger than the area of themain laminate portion 13A but smaller than the area defined by the outerperiphery of the margin portion 13B. The area of a solder-receivableportion 18E is an area of the margin portion 13B excluding the areacovered by the solder-repellent portion 17E. According to the fifthmodification, after the main laminate portion 13A is covered by thesolder-repellent portions 17E, the monolithic capacitor 10 is mounted onthe circuit board 1. Thus, fillets 3 are prevented from being providedover the main laminate portion 13A so as to effectively reducevibrations.

Throughout the first to fifth modifications, preferably, thesolder-receivable portion 18A or 18B, or the solder-receivable portions18C, 18D, or 18E is/are arranged so as to extend over four cornerportions of the end surface portion of the outer electrode 14 as in thecase of the first preferred embodiment illustrated in FIG. 1. Inaddition, preferably, each solder-receivable portion 18A or 18B isarranged such that upper and lower portions of the solder-receivableportion 18A or 18B are symmetrical with respect to the horizontal linepassing through the central portion C of the corresponding end surface15, or, preferably, each pair or set of the solder-receivable portions18C, 18D, or 18E is arranged such that upper ones and lower ones of thesolder-receivable portions 18C, 18D, or 18E are symmetrical with respectto the horizontal line passing through the central portion C of thecorresponding end surface 15.

The above-described preferred embodiment and non-limiting exemplarymodifications do not limit the present invention defined in the claimsand can be modified in various manners within a scope of the presentinvention. Although a typical monolithic capacitor 10 is described as anexample in the first preferred embodiment, preferred embodiments of thepresent invention are also applicable not only to a monolithic capacitor10 including two outer electrodes 14 but also to a three-terminalmonolithic capacitor having three outer electrodes 14, for example. Inaddition, preferred embodiments of the present invention are applicablenot only to the monolithic capacitor 10 but also to general monolithicceramic electronic components including a monolithic LC filter, forexample.

Second Preferred Embodiment

In a monolithic capacitor 20 according to a second preferred embodimentof the present invention, each outer electrode is arranged so as tocover a portion but not all of the corresponding end surface 15. Thecomponents that are the same as those in the first preferred embodimentare not described in detail.

As illustrated in FIG. 8, when the monolithic capacitor 20 is viewedfrom one of the end surfaces 15, the outer electrode 24 has a square orsubstantially square shape so as to cover a portion of the end surface15 of the laminate body 13. The outer electrode 24 is preferably formedby a plating or printing transfer process, for example.

A solder-repellent portion 27 is arranged so as to cover the centralportion C of the end surface 15 of the laminate body 13. Thesolder-repellent portion 27 has a circular or substantially circularshape that is smaller than the area of the outer electrode 24. Thesolder-repellent portion 27 is defined by a circular or substantiallycircular solder-resistant film 29 attached to the surface of the outerelectrode 24. A solder-receivable portion 28 includes portions disposedon two opposing sides of the solder-repellent portion 27 in the verticalor widthwise direction so as to sandwich the solder-repellent portion27.

In the second preferred embodiment, as in the case of the firstpreferred embodiment, the solder-receivable portion 28 is preferablyarranged so as to extend over at least four corner portions of the outerelectrode 24. Also preferably, the solder-receivable portion 28 isconfigured such that the two opposing sides of the solder-receivableportion 28 in the vertical direction are symmetrical with each other.

According to the second preferred embodiment, molten solder does notadhere to portions around the central portion C of the end surfaces 15of the laminate body 13. Thus, expansion and contraction that occurs asa result of application of an AC voltage is not significantlytransmitted to the circuit board 1. Consequently, vibrations of thecircuit board 1 are reduced and acoustic noise is less likely to begenerated. Further, the molten solder adheres to the solder-receivableportions 28. Thus, fillets 3 are provided so as to connect thesolder-receivable portions 28 to the circuit board 1, thus securelyconnecting the monolithic capacitor 20 and the circuit board 1 together.

The monolithic capacitor 20 according to the second preferred embodimentcan be appropriately modified with regard to the shape of the outerelectrodes 24 and/or the shape of the solder-repellent portions 27.FIGS. 9 and 10 illustrate monolithic capacitors according to some ofexemplary modifications of a preferred embodiment of the presentinvention.

FIG. 9 illustrates a monolithic capacitor 20 according to a sixthmodification of a preferred embodiment of the present invention in whichthe outer electrodes 24 are modified. In FIG. 9, when the monolithiccapacitor 20 is viewed from one of the end surfaces 15, an outerelectrode 24A is circular or substantially circular. Thesolder-repellent portion 27A is arranged so as to cover the centralportion C of the end surface 15. The solder-repellent portion 27A has acircular or substantially circular shape that is smaller than the outerelectrode 24A. The solder-repellent portion 27A is defined by a circularor substantially circular solder-resistant film 29A attached to thesurface of the outer electrode 24A. A solder-receivable portion 28Aincludes portions disposed on two opposing sides of the solder-repellentportion 27A in the vertical or widthwise direction so as to sandwich thesolder-repellent portion 27A. Preferably, the solder-receivable portion28A is configured such that upper and lower portions are symmetricalwith each other.

FIG. 10 illustrates a monolithic capacitor 20 according to a seventhmodification of a preferred embodiment of the present invention in whichthe outer electrodes 24 are modified. In FIG. 10, when the monolithiccapacitor 20 is viewed from one of the end surfaces 15, the outerelectrode 24B has a strip shape extending in the vertical direction andincluding a middle portion that protrudes in the widthwise direction.Each outer electrode 24B covers a portion of an upper surface 8 and alower surface 9 of the monolithic capacitor 20. A solder-repellentportion 27B is arranged so as to cover the central portion C of the endsurface 15 of the laminate body 13. The solder-repellent portion 27B isrectangular or substantially rectangular. The solder-repellent portion27B is provided on the surface of the outer electrode 24B and the endsurface 15 by attaching a substantially rectangular solder-resistantfilm 29B to the surface of the outer electrode 24B and the end surface15. Solder-receivable portions 28B are located on two opposing sides ofthe solder-repellent portion 27B in the vertical direction so as tosandwich the solder-repellent portion 27B.

Preferably, but not necessarily, the solder-receivable portions 28B arearranged such that the upper one and the lower one of thesolder-receivable portions 28B are symmetrical with each other. Evenwhen the outer electrode 24B is configured such that the upper and lowerportions are not symmetrical, such as a trapezoidal shape, for example,as long as the solder-repellent portion 27B is arranged so as to coverthe central portion C of the end surface 15, a fillet 3 can be preventedfrom being provided over a portion of the monolithic capacitor 20 thatexpands and contracts to a large extent when an AC voltage is applied tothe monolithic capacitor 20.

In the seventh modification, each solder-resistant film 29B is providedon the dielectric ceramic layers 11 on the corresponding end surface 15of the laminate body 13. With this configuration, the solder-resistantfilm 29B is securely adhered to the end surface 15 of the laminate body13 and thus the solder-repellent portion 27B is less likely to bedisplaced or detached under high temperature conditions such as insoldering.

Third Preferred Embodiment

In a monolithic capacitor 30 according to a third preferred embodimentof the present invention, solder-repellent portions are also providedover portions of the outer electrode 14 on side surfaces 16 (theseportions will be referred to as side surface portions, below).Components that are the same as those in the first preferred embodimentare not described in detail.

As illustrated in FIG. 11, when the monolithic capacitor 30 is viewedfrom the side surface 16, a solder-repellent portion 37 is arranged soas to extend over a portion of the side surface portion of each outerelectrode 14. The solder-repellent portion 37 is defined by arectangular or substantially rectangular solder-resistant film 39attached to the surface of the side surface portion of the outerelectrode 14. A solder-receivable portion 38 includes portions disposedon two opposing sides of the solder-repellent portion 37 in the verticaldirection so as to sandwich the solder-repellent portion 37. Here, whenthe monolithic capacitor 30 is viewed from either one of the endsurfaces 15, the monolithic capacitor 30 looks substantially the same asthat in the case of the first modification (FIG. 3).

FIG. 12 illustrates a state in which the monolithic capacitor 30according to the third preferred embodiment is mounted on the circuitboard 1 via solder 2. As illustrated in FIG. 12, molten solder adheresto the solder-receivable portions 38 of the monolithic capacitor 30, sothat fillets 3 are provided so as to connect the solder-receivableportions 38 to the circuit board 1. However, the molten solder does notadhere to the solder-repellent portions 37, that is, the portions aroundthe central portion C of the end surfaces 15 and the side surfaceportions, so that fillets 3 are not provided over these portions.

When an AC voltage is applied to the monolithic capacitor 30, not onlythe end surfaces 15 but also side surfaces expand and contract, asillustrated in FIG. 16. Since molten solder does not adhere to the sidesurface portions according to the third preferred embodiment, asillustrated in FIG. 12, expansion and contraction that occurs as aresult of application of an AC voltage is not significantly transmittedto the circuit board 1. Consequently, vibrations of the circuit board 1are reduced and acoustic noise is less likely to be generated.

The monolithic capacitor 30 according to the third preferred embodimentcan be appropriately modified with regard to the position and/or theshape of the solder-repellent portions 37. FIGS. 13 and 14 illustratemonolithic capacitors 30 according to some non-limiting exemplarymodifications.

FIG. 13 illustrates a monolithic capacitor 30 according to an eighthmodification of a preferred embodiment of the present invention in whichthe solder-repellent portions 37 are modified. In the monolithiccapacitor 30 according to the eighth modification, solder-repellentportions 37A are arranged so as to extend over a portion of the uppersurface portion, the lower surface portion, and two side surfaceportions of the outer electrode 14. On each of the side surfaces 16, thecorresponding solder-receivable portion 38A includes portions disposedon two opposing sides of the solder-repellent portion 37A in thevertical direction so as to sandwich the solder-repellent portion 37A.On each of the upper surface 8 and the lower surface 9, thecorresponding solder-receivable portion 38A includes portions disposedon two opposing sides of the solder-repellent portion 37A in thewidthwise direction so as to sandwich the solder-repellent portion 17A.When the monolithic capacitor 30 illustrated in FIG. 13 is viewed fromeither one of the end surfaces 15, the monolithic capacitor 30 lookssubstantially the same as that in the case of the fourth modification(FIG. 6).

A solder-repellent portion 17D arranged on the end surface 15 and thesolder-repellent portions 37A arranged on the upper surface 8, the lowersurface 9, and the side surfaces 16 are defined together by asolder-resistant film 39A attached to these surfaces. Thesolder-resistant film 39A is preferably attached by print-transferring apaste material having a rhombic or substantially rhombic shape to thesurfaces of the outer electrode 14 from the end surface 15 using arubber product, for example. According to this manufacturing method, thesolder-repellent portions 17D and 37A can be formed concurrently andefficiently.

FIG. 14 illustrates a monolithic capacitor 30 according to a ninthmodification of a preferred embodiment of the present invention in whichthe solder-repellent portions 37 are modified. In the monolithiccapacitor 30 according to the ninth modification, when the monolithiccapacitor 30 is viewed from one of the side surfaces 16, thesolder-repellent portion 37B is arranged so as to extend over a portionof the side surface portion of the outer electrode 14. Thesolder-repellent portion 37B is defined by a strip-shapedsolder-resistant film 39B attached to the surface of the side surfaceportion of the outer electrode 14. Solder-receivable portions 38B arearranged on two opposing sides of the solder-repellent portion 37B inthe vertical direction so as to sandwich the solder-repellent portion37B. When the monolithic capacitor 30 illustrated in FIG. 14 is viewedfrom either one of the end surfaces 15, the monolithic capacitor 30looks substantially the same as that according to the secondmodification (FIG. 4).

The solder-resistant film 39B is provided on a portion of some of thedielectric ceramic layers 11 on the side surfaces 16 of the laminatebody 13. Consequently, the solder-resistant film 39B is securely adheredto the side surface 16 of the laminate body 13 and the solder-repellentportion 37B is less likely to be displaced or detached under hightemperature conditions such as in soldering.

Fourth Preferred Embodiment

In a monolithic capacitor 40 according to a fourth preferred embodimentof the present invention, the outer electrodes 14 are themselves notsubjected to a molten-solder repelling process. Components that are thesame as those in the first preferred embodiment are not described indetail.

As illustrated in FIG. 15, each solder-repellent portion 47 is providedin a portion of the corresponding outer electrode 14 of the monolithiccapacitor 40. The solder-repellent portion 47 is provided by oxidizing adesired portion of the outer electrode 14. This oxidization preventsmolten solder from adhering to the solder-repellent portion 47.

When the monolithic capacitor 40 is viewed from either one of the endsurfaces 15, the solder-repellent portion 47 is arranged so as to coverthe central portion C of the end surface 15 of the laminate body 13. Asolder-receivable portion 48 includes portions disposed on two opposingsides of the solder-repellent portion 47 in the vertical or widthwisedirection so as to sandwich the solder-repellent portion 47.

Specifically, when the monolithic capacitor 40 is viewed from either oneof the end surfaces 15, preferably, the outer electrode 14 has aquadrangular or substantially quadrangular shape and thesolder-repellent portion 47 has a circular or substantially circularshape. Four corner portions of the outer electrode 14 are not oxidizedand thus allow molten solder to adhere thereto. The solder-receivableportion 48 is configured such that upper and lower portions aresymmetrical with respect to the horizontal line passing the centralportion C.

In the monolithic capacitor 40 according to the fourth preferredembodiment, molten solder does not adhere to portions around the centralportion C of the end surfaces 15. Thus, expansion and contraction thatoccur as a result of application of an AC voltage are not significantlytransmitted to the circuit board 1. Consequently, vibrations of thecircuit board 1 are reduced and acoustic noise is less likely to begenerated. Further, since the molten solder adheres to thesolder-receivable portions 48, fillets 3 are provided so as to connectthe solder-receivable portions 48 to the circuit board 1, thus securelyconnecting the monolithic capacitor 40 and the circuit board 1 together.

The solder-repellent portion 47 is formed by fixing the monolithiccapacitor 40 to a jig and then irradiating a portion of the end surfaceportion of the outer electrode 14 with a laser beam. By being irradiatedwith a laser beam, the surface of the outer electrode 14 is oxidized.The monolithic capacitor 40 made by the method involving the oxidizationprocess can achieve the same or substantially the same effects as thoseachieved by the monolithic capacitor 10 according to the first preferredembodiment without including an additional component such as thesolder-resistant film 19, 29, or 39.

As in the case of the monolithic capacitors 10 to 30 according to thefirst to third preferred embodiments, the monolithic capacitor 40according to the fourth preferred embodiment can be appropriatelymodified with regard to the position or the shape of thesolder-repellent portion 47 and the solder-receivable portion 48.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A monolithic ceramic electronic componentcomprising: a ceramic laminate body having a cuboid or substantiallycuboid shape and including dielectric ceramic layers and internalelectrodes alternately stacked on top of one another, the ceramiclaminate body including an outer periphery defined by an upper surface,a lower surface, two side surfaces, and two end surfaces that areperpendicular or substantially perpendicular to the upper surface, thelower surface, and the two side surfaces; and an outer electrodearranged at least over one of the end surfaces so as to be electricallyconnected to the internal electrodes; wherein the outer electrodeincludes a solder-repellent portion to which molten solder does notadhere and a solder-receivable portion to which the molten solder doesadhere; and when the monolithic ceramic electronic component is viewedfrom the end surface over which the outer electrode is arranged, thesolder-repellent portion is arranged so as to cover a central portion ofthe end surface; and the solder-receivable portion includes portionsdisposed on two opposing sides of the solder-repellent portion so as tosandwich the solder-repellent portion.
 2. The monolithic ceramicelectronic component according to claim 1, wherein when the monolithicceramic electronic component is viewed from the end surface over whichthe outer electrode is arranged, the outer electrode has a quadrangularor substantially quadrangular shape; and the solder-receivable portionis arranged so as to extend over four corner portions of the outerelectrode.
 3. The monolithic ceramic electronic component according toclaim 1, wherein when a direction in which the dielectric ceramic layersare stacked is a vertical direction and the monolithic ceramicelectronic component is viewed from the end surface over which the outerelectrode is arranged, the solder-receivable portion is configured suchthat upper and lower portions of the solder-receivable portion in thevertical direction are symmetrical with each other.
 4. The monolithicceramic electronic component according to claim 1, wherein the ceramiclaminate body includes a main laminate portion and a margin portionprovided around the main laminate portion, the main laminate portionincluding the dielectric ceramic layers and the internal electrodes thatare alternately stacked on top of one another and are into contact withone another, and the margin portion includes the dielectric ceramiclayers that are stacked on top of one another; and when the monolithicceramic electronic component is viewed from the end surface over whichthe outer electrode is arranged, an area of the solder-repellent portionis larger than an area of the main laminate portion but smaller than anarea defined by an outer periphery of the margin portion.
 5. Themonolithic ceramic electronic component according to claim 1, whereinthe outer electrode covers a portion of the ceramic laminate body, theportion extending from the end surface to portions of the upper surface,the lower surface, and the two side surfaces; and wherein when themonolithic ceramic electronic component is viewed from one of the twoside surfaces over which the outer electrode is arranged, thesolder-repellent portion is arranged so as to extend partially over aportion of the outer electrode provided on the side surface.
 6. Themonolithic ceramic electronic component according to claim 1, whereinthe solder-repellent portion is defined by a solder-resistant filmattached to the outer electrode.
 7. The monolithic ceramic electroniccomponent according to claim 6, wherein the solder-resistant film ismade of a heat-resistant resin that is not deformed at a solderingtemperature.
 8. The monolithic ceramic electronic component according toclaim 1, wherein the solder-repellent portion is defined by an oxidizedportion of the outer electrode.
 9. The monolithic ceramic electroniccomponent according to claim 1, wherein the solder-receivable portion isprovided in a portion of the outer electrode that is exposed to outside.10. The monolithic ceramic electronic component according to claim 1,wherein the solder-repellant portion is circular or substantiallycircular.
 11. The monolithic ceramic electronic component according toclaim 1, wherein the outer electrode includes three layers of copper,nickel, and tin, or copper nickel, and gold.
 12. The monolithic ceramicelectronic component according to claim 1, wherein the dielectric layersare made of a ferroelectric material.
 13. The monolithic ceramicelectronic component according to claim 1, wherein the dielectric layersare made of barium titanate.
 14. The monolithic ceramic electroniccomponent according to claim 6, wherein the solder-resistant film has arectangular or substantially rectangular shape.
 15. The monolithicceramic electronic component according to claim 6, wherein thesolder-resistant film has a widthwise-extending strip shape.
 16. Themonolithic ceramic electronic component according to claim 6, whereinthe solder-resistant film has a vertically-extending strip shape. 17.The monolithic ceramic electronic component according to claim 6,wherein the solder resistant film has an octagonal or substantiallyoctagonal shape.
 18. The monolithic ceramic electronic componentaccording to claim 1, wherein the outer electrode is arranged to cover aportion but not all of one of the end surfaces.
 19. The monolithicceramic electronic component according to claim 18, wherein the outerelectrode has a square or substantially square shape.
 20. The monolithicceramic electronic component according to claim 19, wherein thesolder-repellant portion has a circular or substantially circular shapeextending over an area that is smaller than an area of the outerelectrode.